Annular preventer

ABSTRACT

An annular preventer blowout preventer (BOP) that can seal off a wellbore for controlling and monitoring oil and gas wells. The BOP is a latch type annular preventer with a body, a inner, a piston, and a rubber packing element. The preventer seals around drill pipe and in some instances against an open well bore. A plurality of latches and inner screws secure the lid to the body and further prevent rotation.

FIELD OF THE INVENTION

The present invention relates to oil and gas blow out preventers (BOP), and more specifically, to a latched head annular BOP.

BACKGROUND OF THE INVENTION

Annular preventers are a type of blowout preventer (BOP) that can seal off a wellbore. An annual preventer is a large, specialized valve used to seal, control and monitor oil and gas wells. It is usually installed above the ram preventers that forms a seal in the annular space between the pipe and wellbore. If no pipe is present, it may be installed over the wellbore itself. The annular preventer consists of a body, a cap, a piston and a rubber packing element.

They are effective for maintaining a seal around a drill pipe through use of hydraulic pressure to squeeze a packing element to seal drill pipe. The annular preventer surrounds the pipe and uses a wedge principle to seal off the pipe in the case the well needs to be shut in. Hydraulic pressure drives a piston upward or downward respectively which in turn causes a packing element to seal or release the pipe.

The sealing element is mechanically squeezed inward to seal on pipe, drill collars, casing, tubing, and the like. Annular preventers advantageously can seal varying size of pipe as compared to a ram type BOP. Many BOP stacks contain one or more annular preventers at the top of the stack. If a kick or blow out is detected or determined imminent, the annular preventer may be closed first prior to ram BOPs.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an annular preventer that allows faster replacement of a lid on the body of the preventer while maintaining a secure seal during operation.

Another object of the present invention is to provide an annular preventer with a lid that is secured to resist lateral movement when in operation.

Yet another object of the present invention is to provide an annular preventer that is sized to allow the use of smaller diameter drill pipe.

One general aspect comprises an annular preventer. The annular preventer comprises a body defining a throughbore. The annular preventer also comprises a lid that fits onto the body. The lid has a replaceable wear plate. The lid and the body define a chamber therein with a first interior cylindrical surface within the lid and a second interior cylindrical surface within the body. The annular preventer also comprises a plurality of latches mounted around a circumference of the body that extend through the body. The latches have retractable jaws that engage corresponding latching surfaces on the lid to selectively secure the lid to the body. The annular preventer also comprises a conical packing element with an opening therethrough operable to receive a pipe extending through the throughbore. The pipe, when present, defines an annulus between the throughbore and the pipe. The annular preventer also comprises a piston mounted in the body for movement in an axial direction parallel to an axis through the throughbore. The piston defines an interior conical receptacle that receives the conical packing element. The piston has an exterior piston member that moves within an annular piston chamber formed between the piston and the body. The piston has a first exterior cylindrical surface and a second exterior cylindrical surface that engage the first interior cylindrical surface and the second interior cylindrical surface. The annular preventer also comprises a cage that engages the conical packing element to secure the conical packing element between the cage and the wear plate. Hydraulic connections are on either side of the exterior piston member that extend through the body. The piston is movable in the axial direction in response to hydraulic fluid to selectively compress the conical packing element to seal the annulus around the pipe. A plurality of cap screws extend through the lid to engage the body to prevent rotation of the lid with respect to the body.

Implementations may include one or more of the following features: the annular preventer further has a flange on the lid. A plurality of cap screws extend through the flange. The annular preventer further has a top surface of the body that engages the flange. A seal is on the exterior piston member that engages a cylindrical piston chamber wall. In one embodiment, the throughbore has a diameter of 7 1/16 inches.

The annular preventer may comprise each latch of a plurality of latches further with an outer screw disposed within the latch. The latch may pass through the body. The outer screw may be threaded. A socket head may be on a terminal end of the outer screw outside relative the body where upon rotation of the socket head rotates the outer screw along an axis inward and outward relative the body. A seal may be mounted around the outer screw which seals the outer screw within the body when engaged. An inner screw may be mounted internally within the outer screw. The inner screw may be operably attached to the retractable jaw. A second seal may be mounted within the inner screw which seals with the outer screw. The retractable jaws further comprise an internal set of teeth moveably mounted within the body. A corresponding external latching surface may be formed on the lid. The corresponding external latching surface comprises an external set of corresponding teeth operable to receive the internal set of teeth from the retractable jaw to secure or loosen the body and the lid. The annular preventer further comprises a shoulder between the outer screw and the inner screw where rotation of the outer screw and engagement at the shoulder urges the outer screw radially outward to retract the internal set of teeth from the external set of corresponding teeth.

BRIEF DESCRIPTION OF THE DRAWINGS

The general description listed above and following detailed description is merely illustrative of the generic invention. Additional modes, advantages, and particulars of this invention will be readily suggested to those skilled in the art without departing from the spirit and scope of the invention. A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts and wherein:

FIG. 1 is a side cross-sectional view of an annular preventer in accord with one possible embodiment of the present invention.

FIG. 2 is close up side view of one embodiment of a latch for an annular preventer in accord with one possible embodiment of the present invention.

FIG. 3 is a top view of an annular preventer with a plurality of latches utilized to secure the lid to the body of annular preventer in accord with one possible embodiment of the present invention.

FIG. 4 is side cross sectional view of a lid secured to the body of an annular preventer utilizing in accord with one possible embodiment of the present invention.

FIG. 5 is a perspective view of an annular preventer in accord with one possible embodiment of the present invention.

DESCRIPTION OF THE INVENTION

Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner.

Turning to FIG. 1, the four basic segments of the annular preventer 100 are the top or lid 2, body 1, piston 3, and packing element 11. The preventer seals around drill pipe 58 with axis 57 and in some instances against an open well bore. A close port 36 allows hydraulic fluid to flow that pushes an internal piston 3 upwardly in FIG. 1 to compress the seal around the pipe 58. An open port 26 releases the seal by causing the piston 3 to move downwardly in FIG. 1. In other words, when the preventer's closing mechanism is actuated, hydraulic pressure is applied to the piston 3, causing it to slide upward and force the packing element to extend into the wellbore around the drill pipe 58. As the hydraulic fluid is pumped into the close port 36, the packing element 11 squeezes the pipe or tubular within. The preventer packing element 11 is released by applying hydraulic pressure in a manner that slides the piston 3 downward and allows the packing element 11 and piston 3 to return to its original position. The packing element 11 may also be referred to as packing unit or the like, During opening, hydraulic fluid is pumped into the open port 26 thereby causing the packing element 11 to be pushed down resulting in releasing the tubular. Wear on the seals along the piston 3, lid 2 and body 1, as well as on wear plate 4 requires replacement whereupon lid 2 of the preventer has to be removed.

One of skill will appreciate that there are only two moving parts, piston 3 and packing unit 11, on the annular BOP 100 which means few areas are subject to wear. Therefore the BOP is safer and more efficient, requiring less maintenance, and less downtime.

Lid 2 comprises a cap that is secured to body 1. The lid may be made of metal or other suitable material able to withstand the pressures exerted during oil and gas operations. The lid 2 is a clamp type design which is a simple, efficient, and strong method of connecting the lid 2 to the body 1 for safe operation with. Lid 2 and body 1 define a throughbore 54 with through axis 57. Drill pipe 58 may pass through the throughbore and is smaller in diameter than the diameter 40 of throughbore 54.

Pressure energized seals 64 are used for dynamically sealing piston chamber 46 to provide safe operation, long seal life, and less maintenance. Seals 64 are formed within exterior piston members 48. Exterior piston member 48 protrudes outward relative piston 3 into annular piston chamber 46 and is sealed with seals 64. Annular piston chamber 46 is formed on the outside of piston 3 between lid 2 and body 1. Annular piston chamber 46 receives hydraulic fluid which is pumped from open port 26 and close port 36. A surface hook up may used to connect the hydraulic lines to the opening and closing chambers 45, 49 of the BOP 100. Open chamber 45 is within annular piston chamber 46 and in one embodiment is the upper chamber relative close chamber 49 separated by exterior piston member 48 as shown in FIG. 1. The open chamber and close chamber are defined by piston cylindrical surface 62, exterior piston member 48 and the body 1.

Pressure applied to the closing chamber 49 raises the piston 3 and affects the initial seal between the packing unit 11 and drill pipe 58. Well pressure or test pressure also acts on the piston 3 below the sealed off packing unit 11 and further increases the closing force acting on the packing unit 11. As the well pressure or test pressure exceeds the required level, the preventer 100 is maintained closed by the well pressure alone. As well pressure increases, the closing force on the packing unit 11 also increases. Closing pressure should be proportionally reduced as well pressure is increased in order to maintain optimum closing force on the packing unit 11 and prolong packing unit 11 life.

During normal drilling operations, it is recommended that the pressure regulator valve for the preventer 100 be set at the initial closing pressure for the size pipe being use. This pressure will ensure that initial seal off is achieved should a “kick” be encountered.

The lid 2 further comprises a replaceable wear plate 4 on the interior of lid 2. The wear plate 4 may be a field replaceable wear plate in the BOP lid 2 which serves an upper non-sealing wear surface for the movement of the packing unit 11, making field repair fast and economical. Packing unit 11 may also be referred to as a packing element. The lid 2 and the body 1 define a chamber therein with a first interior cylindrical surface 42 within said lid 2 and a second interior cylindrical surface 50 within said body 1. Piston 3 comprises corresponding first exterior cylindrical surface 44 and second exterior cylindrical surface 52 which are in engagement with the first interior cylindrical surface 42 within said lid 2 and the second interior cylindrical surface 50 within said body 1.

Conical bowl design of the piston 3 provides a simple and efficient method of closing the packing unit 11. In one embodiment, the piston 3 serves as a sealing surface against the rubber packing unit 11, therefore there is no metal to metal wear on the sealing surface and thus longer life results. Packing element 11 is secured within the chamber formed by lid 2 and body 1. Piston 3 has a conical receptacle 60 that is operable to receive the packing element 11. Packing element 11 is a conical packing element comprising an opening therethrough operable to receive a pipe 58 extending through the throughbore 54. The pipe 58, when present, defines an annulus 56 between the throughbore 54 and the pipe 58.

Within annular BOP 100 may be a cage 10 that engages the conical packing element 11 to secure the conical packing element 11 between the cage 10 and the wear plate 4. Ferry head cap screw 22 may secure cage 10 to body 1 thereby aiding the proper orientation of packing element 11 within chamber 55.

The lid 2 may have various seals or gaskets such as lid gasket 12 and O-ring 13 to prevent fluid from leaking or foreign substances from being introduced during operation.

The packing element 11 may be manufactured from high quality rubber, reinforced with flanged steel segments. Each unit may have a large volume of tough, feedable rubber to meet any requirement.

The molded in steel segments may have flanges at the top and bottom. These segments anchor the packing element 11 within the blowout preventer 100 and control rubber extrusion and flow when sealing off well pressures. Because the rubber is confined and kept under compression, it is resistant to tears, cuts, and abrasion.

As shown in FIG. 3, the present invention has a ring of latches 23 for the top 2 that allows the top 2 to be removed for replacement of the internal seal. A plurality of latches 23 are mounted around a circumference of the body 1 which extend through the body 1. The latches 23 comprise retractable jaws 5 with latching surfaces 31 that engage corresponding latching surfaces 30 on said lid 2 to selectively secure the lid 2 to the body 1. The latches 23 will be further discussed in FIGS. 2 and 3.

FIG. 3 is a top view of annular preventer 100 and shows a plurality of latches 23 utilized to secure the lid to the body of annular preventer 100. The ring of latches allows the top to be removed quickly saving considerable time during maintenance and repair. It will be appreciated by those of skill that having a plurality of latches 23 allows for easy removal and replacement of the top during maintenance or other instances in which the lid 2 must be removed from body 1. Lid 2 is further secured to the annular body 1 in one embodiment by four cap screws 27. In other possible embodiments, more than or less than four cap screws 27 may be used to prevent rotation of the cap and further secure the cap in place.

Looking at FIG. 2, the dashed section of FIG. 1 is blown up in more detail for one embodiment of a latch 23 for the preventer 100. Only one latch 23 is described but all are preferably the same. Jaw operating screw 6 and jaw holding cap screw 7 are disposed within body 1. of preventer 100 and accessed by pressure plug socket head 21 to force latching surface or latch teeth 31 on jaw 5 to engage with corresponding latching surface or lid teeth 30 which may also be referred to as a corresponding external latch surface. Teeth 31 may be referred to as an internal set of teeth and teeth 30 may be referred to as a set of external teeth. Pressure plug socket head 21 is on a terminal end of the operating screw opposite the jaws. Each set of teeth are corresponding relative each other such that they are operable to interlock or secure to each other. This secures lid 2 to body 1. Jaw operating screw 6 is threadably secured within an opening through the body 1. Jaw operating screw 6 may also be referred to outer screw and jaw holding cap screw 7 may also be referred to as inner screw. Jaw operating screw 6 can be rotated within body 1 to compress jaw 5 onto the latching surface 30 formed on lid 2 Jaw holding cap screw 7 is inserted through an opening through jaw operating screw 6. One end of jaw holding cap screw 7 may be connected to jaw 5 by any suitable means such as threads, internal latches (not shown) or the like. Thus a shoulder between jaw holding cap screw 7 and jaw operating screw 6 may be used for retraction of jaw 5 from latch teeth 31. Jaw holding cap screw 7 is rotatable within jaw operating screw 6. O-rings 8 and 9 may be utilized to seal the latch 23 against the body 1 of preventer 100 when engaged. Seal 8 is between Jaw operating screw or outer screw 6 and jaw holding cap screw or inner screw 7. The lid 2 is further secured to the body 1 utilizing cap screws 27 in addition to clamps 23 as depicted in FIGS. 4 and 5. After lid 2 has been placed onto body 1, jaws 5 are tightened to engage latching surfaces 30 formed within lid 2 and latching surfaces 31 on the interior surface of jaw 5 within body 1. Pressure plug socket head 21 may be rotated which in turn rotates jaw operating screw 6 inward or outward along axis 33 depending on the rotation of pressure plug socket head 21. Jaw operating screw 6 is threaded within the wall of body 1 and allows for rotation along axis 33 during rotation of pressure plug socket head 21.

Turning to FIG. 4, a side cross sectional view is shown of lid 2 secured to the body 1 of an annular preventer 100 in accord with one possible embodiment of the present invention. As described above, body 1 comprises a plurality of latches 23 around the circumference of the body 1. The latches 23 pass through the body 1 and terminate with jaws 5. Jaws 5 comprises latching surfaces 31 which engage corresponding latching surfaces 30 of lid 2. The jaws may be tightened by rotation of screws thereby moving the jaws inward towards lid 2 until each respective latching surface is engaged to fully secure lid 2 to body 1. To further secure lid 2 to body 1, cap screws 27 pass through flange 66 of lid 2 and into a receptacle within top surface 47 of body 1. The cap screws are then tightened thereby preventing rotation of the lid 2.

FIG. 5 is a perspective view of an annular preventer 100 in accord with one possible embodiment of the present invention. This view shows a fully assembled annular 100 ready to be placed into operation. As shown, lid 2 has been secured to body 1 by tightening the plurality of latches 23 around the circumference of body 1 and cap screws 27 around the circumference of lid 2. Studs 24 and nuts 25 are ready for mounting of a equipment or pipes to annular 100. Open port 26 and close port 36 are also ready for hydraulic lines to be secured to allow fluid to be pumped for operation of the piston and packing unit within chamber 55.

By decreasing the amount of time necessary for repair and/or replacement, the present invention allows a rig to resume normal drilling functions quicker thereby preventing further idle downtime and the associated costs, i.e. lost profits, operator safety concerns during repair, and the like.

The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description only. It is not intended to be exhaustive or to limit the invention to the precise form disclosed; and obviously many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.

In general overview of the drawings, it will be understood that such terms as “up,” “down,” “vertical,” and the like, are made with reference to the drawings and/or the earth and that the devices may not be arranged in such positions at all times depending on variations in operation, transportation, mounting, and the like. As well, the drawings are intended to describe the concepts of the invention so that the presently preferred embodiments of the invention will be plainly disclosed to one of skill in the art but are not intended to be manufacturing level drawings or renditions of final products and may include highly simplified conceptual views and exaggerated angles, sizes, and the like, as desired for easier and quicker understanding or explanation of the invention.

One of skill in the art upon reviewing this specification will understand that the relative size, orientation, angular connection, and shape of the components may be greatly different from that shown to provide illuminating instruction in accord with the novel principals taught herein. As well, connectors, component shapes, and the like, between various housings and the like may be oriented or shaped differently or be of different types as desired. Many additional changes in details, components, steps, and organization of the system and method, herein described and illustrated to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention. It is therefore understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 

What is claimed is:
 1. An annular preventer, comprising a body defining a throughbore; a lid that fits onto said body, said lid comprising a replaceable wear plate, said lid and said body defining a chamber therein with a first interior cylindrical surface within said lid and a second interior cylindrical surface within said body; a plurality of latches mounted around a circumference of said body that extend through said body, said plurality of latches comprising retractable jaws that engage corresponding latching surfaces on said lid to selectively secure said lid to said body; a conical packing element comprising an opening therethrough operable to receive a pipe extending through said throughbore, said pipe when present defining an annulus between said throughbore and said pipe; a piston mounted in said body for movement in an axial direction parallel to an axis through said throughbore, said piston defining an interior conical receptacle that receives said conical packing element, said piston comprising an exterior piston member that moves within an annular piston chamber formed between said piston and said body, said piston comprising a first exterior cylindrical surface and a second exterior cylindrical surface that engage said first interior cylindrical surface and said second interior cylindrical surface; a cage that engages said conical packing element to secure said conical packing element between said cage and said replaceable wear plate; hydraulic connections on either side of said exterior piston member that extend through said body, said piston being movable in said axial direction in response to hydraulic fluid to selectively compress said conical packing element to seal said annulus around said pipe; and a plurality of cap screws that extend through said lid to engage said body to prevent rotation of said lid with respect to said body.
 2. The annular preventer of claim 1, further comprising a flange on said lid, said plurality of cap screws extending through said flange.
 3. The annular preventer of claim 2, further comprising a top surface of said body that engages said flange.
 4. The annular preventer claim 1, further comprising a seal on said on said exterior piston member that engages a cylindrical piston chamber wall.
 5. The annular preventer of claim 1 wherein said throughbore comprises a diameter of 7 1/16 inches.
 6. The annular preventer of claim 1, wherein each latch of said plurality of latches further comprises an outer screw disposed within said latch which passes through said body, said outer screw being threaded, a socket head on a terminal end of said outer screw outside relative said body whereby upon rotation of said socket head rotates said outer screw along an axis inward and outward relative said body, a seal mounted around said outer screw which seals said outer screw within said body when engaged, an inner screw mounted internally within said outer screw, said inner screw being operably attached to said retractable jaw, a second seal mounted within said inner screw which seals with said outer screw, said retractable jaws further comprise an internal set of teeth moveably mounted within said body, a corresponding external latching surface formed on said lid whereby said corresponding external latching surface comprises an external set of corresponding teeth operable to receive said internal set of teeth from said retractable jaw to secure or loosen said body and said lid.
 7. The annular preventer of claim 6, further comprising a shoulder between said outer screw and said inner screw whereby rotation of said outer screw and engagement at said shoulder urges of said outer screw radially outward to retract said internal set of teeth from said external set of corresponding teeth. 